The present invention relates to an ink jet recording apparatus, and more particularly to an ink jet recording apparatus which ejects ink from an ejection port of a recording head in accordance with an ejection signal to thereby perform a recording operation.
As well known, an ink jet recording system is widely used as a recording system for outputting color images, which is simple in construction and easy in reducing the apparatus size. In a recording apparatus (ink jet printer) based on the ink jet recording system, any of the following systems is usually employed: an electrostatic drive system, a thermal head system, and an electromechanical transducer (piezoelectric) system and others. A fluid material composed of at least colored particles dispersed in a solvent is generally used for a recording liquid (ink) used for recording in the ink jet printer. Recording (printing) is performed such that ink is ejected onto a recording material, such as recording paper, by using the recording system.
As for an ink tank storing the ink, the ink to be supplied to a recording head is not only stored in the ink tank, but also the ink must be constantly stirred in the ink tank so as to prevent colorant-containing particles dispersed in the stored ink from sedimenting in the ink tank and from losing uniformity of the particle dispersion.
With regard to this technique, JP 2002-19148 A discloses an ink jet recording apparatus whose ink tank includes an ink circulation system for stirring oil ink contained in the ink tank, and an ink supply system which is branched from the ink circulation system and supplies the ink to an ejection head, and in which stirring of the ink contained in the ink tank and supply of the ink to the ejection head are performed simultaneously by circulating the ink through the ink circulation system.
JP 2002-273867 A discloses an ink jet recording apparatus in which an ink tank is provided with ink stirring means separately from an ink circulation system in order to prevent ink particles from flocculating and/or sedimenting (more specifically, to prevent large-sized aggregates and/or sediments from being produced from the ink particles) during the circulation of ink in the ink tank.
However, the conventional ink jet recording apparatuses involve the following problems.
In the technique disclosed in JP 2002-19148 A, the ink circulation passage including a circulation pump of a high flow rate and the ink-supplying/recovering passage which is branched from the ink circulation passage are provided outside the ink tank. With provision of those passages, size of a part including the circulation passage is large, and its structure is complicated.
In the technique disclosed in JP 2002-273867 A, the ink stirring means is provided in the ink tank separately from the ink circulation system. Therefore, apparatus cost is increased and a large mounting space is required on the ink tank side.